During the past year, I and my coworkers have continued our work on the control mechanisms, induction and catabolite repression, that regulate D-serine deaminase (Dsdase) synthesis in Escherichia coli K12. The aim is to determine the nature of the elements involved in these processes and their mode of action at the molecular level. Present evidence suggests that the induction control is positive. A lambda-dsd transducing phage has been obtained. The first five amino acids of the N-terminal Dsdase peptide are identical in an operator (dsdO) mutant and in a regulatory (dsdC) mutant. There is a second Dsdase activity in E. coli K12 with very low Vmax for D-serine, which is inducible by D-serine. I chose to develop Dsdase as a simple model system for regulation of gene function, in the expectation that the principles of regulatory mechanisms defined therein might serve as helpful guidelines for the examination of human regulatory diseases such as cancer and certain inborn errors.